1. Field of the Invention
The present invention relates to a circuit apparatus and a method for detecting an earphone in a portable terminal More particularly, the present invention relates to a circuit apparatus and a method for detecting an earphone in a portable terminal that supports both a 3.5 mm four-pole earphone for common use and a 3.5 mm four-pole earphone for use in the USA.
2. Description of the Related Art
Recently, a portable terminal that outputs a stereo sound source now supports voice communication, and also supports a 3.5 mm four-pole earphone having multiple functions in order to control functions of the portable terminal. The 3.5 mm four-pole earphone may be classified as one of a 3.5 mm four-pole earphone for common use and a 3.5 mm four-pole earphone for use in the USA, depending on its pin map.
FIG. 1 illustrates a pin map of a 3.5 mm four-pole earphone according to the related art.
Referring to FIG. 1, the pin map of the 3.5 mm four-pole earphone for common use is configured in the sequence of Left/Right/MICrophone (MIC)/GrouND (GND), and the pin map of the 3.5 mm four-pole earphone for use in the USA is configured in the sequence of Left/Right/GND/MIC. That is, the pin map of the 3.5 mm four-pole earphone for common use and the pin map of the 3.5 mm four-pole earphone for use in the USA are different in their sequence of MIC and GND.
As described above, the pin map of the 3.5 mm four-pole earphone for common use and the pin map of the 3.5 mm four-pole earphone for use in the USA are configured differently. That is, the portable terminal according to the related art includes an earjack that supports only one of the 3.5 mm four-pole earphone for common use and the 3.5 mm four-pole earphone for use in the USA as illustrated in FIG. 2.
FIG. 2 is a view illustrating an earjack that detects a 3.5 mm four-pole earphone according to the related art.
Referring to FIG. 2, an earjack that supports the 3.5 mm four-pole earphone for common use provides the third pole of an earphone as an ear mic EARMIC+ end 201, and the fourth pole as a ground GND 203. In contrast, an earjack that supports the 3.5 mm four-pole earphone for use in the USA provides the third pole of an earphone as a ground GND 211, and the fourth pole as an ear mic EARMIC+ end 213.
Accordingly, in the case of connecting the earphone for use in the USA to a portable terminal that supports the earphone for common use, or connecting the earphone for common use to a portable terminal that supports the earphone for use in the USA, the portable terminal cannot detect the earphone connected thereto. Since the earphone for common use and the earphone for use in the USA are difficult to discriminate with visual inspection, a user may misunderstand a detection problem caused by the above-described erroneous earphone insertion as a malfunction of the portable terminal.